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Sept. 24, 1946.-
J. H FINDLAY ErAL
2,407,979
CONTROLLED ELECTRODE FOR FIELD EMISSION DISCHARGE DEVICES
Filed Sept. 26, 1942
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BY
Www
ATTORNEY
Patented Sept. 24, 1946
2,407,979
UNITED STATES PATENT OFFICE
2,407,979
CONTROLLED ELECTRODE FOR FIELD
EMISSION DISCHARGE DEVICES
John H. Findlay, Upper Montclair, and Clarence
E. Dawley and Andrew Pfei?er, Bloom?eld,
N. J ., assignors to Westinghouse Electric Cor
poration, East Pittsburgh, Pa., a corporation of
Pennsylvania
Application September 26, 1942, Serial No. 459,776
7 Claims. (Cl. 250——2'7 .5)
1
2
The present invention relates to discharge de
vices and more particularly to such devices where
in operation is initiated by a “?eld emission are”
charge substantially constant, and whenever such
voltage tends to vary such is an indication that
the electrode spacing needs readjusting to main
as an electron source, and constitutes an im
tain this constancy of spacing and initiating volt
The structure as shown in such copending
provement 0n the structure such as shown in 51 age.
the copending applications of Charles M. Slack
et al., Ser. No. 412,566, ?led Sept. 27, 1941, and.
Ser. No. 459,775, ?led concurrently herewith, both
application depends primarily for its operation
cathode and anode of the device almost instan
taneously occurs following initiation of the arc
discharge between the starting electrode and
ing operation.
upon the flow of electrical current through a
bimetallic element and therefore might be said
to be electrically controlled.
of which are assigned to the same assignee as
It is the primary object of the present inven
ll)
the present invention.
'
~
tion to provide a discharge device wherein op
In the operation of devices of this character
eration is initiated by a “?eld emission, arc” and
and as pointed out more in detail in the above
the spacing between the electrodes which sup
noted application, Ser. No. 412,566, ?eld emis
port such are discharge is mechanically con
sion of electrons occurs between a pair of “cold”
trolled so as to maintain the electrode spacing
electrodes due to the high potential gradient at
constant.
the cathode. This electrostatic ?eld pulls elec
Another object of the present invention is the
trons from one of the electrodes, which causes a
provision of a discharge device wherein opera
minute are discharge to form between the start
tion is initiated by a “?eld emission are” dis
ing electrode and the cathode, apparently due to
charge and in which movement of the ignition
evolved metallic particles, and the positive ion
electrodes is mechanically controlled exteriorly
bombardment caused by ionization of the evolved
of the device at will by an operator to compen
metal vapor resulting from the are forms a cath
sate for the inherent tendency for the electrode
ode spot which reduces the impedance of the
spacing to increase due to loss of material dur
device, and an electron discharge between the
cathode.
’
A further object of the present invention is
the provision of a discharge device wherein op
eration is initiated by a “?eld emission are” dis
charge between a pair of ignition electrodes and
In a device of this character it inherently fol
lows that a certain amount of material will be 30 in which the voltage required to initiate the “?eld
emission are” is maintained substantially con
lost from and transferred between the closely
stant despite an inherent tendency for the spac
spaced electrodes between which the “field emis
ing between the electrodes to increase due to
sion arc” is initiated. This is because operation
loss of electrode material by mechanically ad
of a “?eld emission arc” discharge device does
not depend upon the ionization of volume gases 35 justing the electrode spacing ex-teriorly of the
device at the will of an operator.
or vapors within the device, but is dependent
Still further objects of the present invention
primarily on positive ions which are the result
will become obvious to those skilled in the art
of the vaporized material from one of, the elecby reference to the accompanying drawing where
trodes interacting with the ?eld emission elec
trons. rlT'he positive ions are necessary to re 40 m:
Fig. 1 is a sectional view in elevation of a device
lieve space charge and to increase the ?eld con
constructed in accordance with the present in
centration at the cathode spot which in turn pro
vention wherein operation is initiated by a “?eld
duces more ?eld and Schotky electrons. Inas
emission are” discharge showing a mechanical
much as a voltage of suf?cient magnitude, de
pending upon the initial spacing of the starting 45 control of the spacing‘ between the electrodes as
well as‘ a schematic diagram of an operating
electrode and cathode, is required to initiate the
circuit.
?eld emission are discharge, there is a tendency
Fig; 2 is a sectional view taken on the lines
for such voltage to increase as the electrodes wear
II—II of Fig. 1 and looking in the direction in
away during operation of the device.
In the above noted copending application Ser. 50 dicated by the arrows, and
Fig. 3 is a sectional view taken on the lines
No. 459,775,, ?led concurrently herewith, a struc
I1'I——III of Fig. 1 and looking in the direction
ture is shown and claimed for maintaining the
indicated by the arrows.
electrode spacing constant during the life of such
device which inherently maintains the voltage
required to initiate the ?eld emission are dis
Referring now to the drawing in detail, the dis
55 charge device 4 as shown in Fig. 1 comprises an
2,407, 979
3
envelope 5 of vitreous material provided with a
pair of electrodes 6 and ‘l which are of substan
tially rectangular con?guration and of uniform
cross section disposed parallel to each other
and having their edges spaced apart a minute
distance of less than approximately .010 inch,
depending upon the voltage to be applied. These
electrodes 6 and ‘I are formed of suitable metal
such as copper, gold, silver, uranium, or the like,
and welded or otherwise secured to leading-in
and supporting conductors 8 and 9. The leading
in and supporting conductor 8 is Welded, soldered,
source of supply such, for example, as shown
more in detail in the above noted copending ap
plication, Ser. No. 459,775, so that when the pri
mary winding 26 is periodically energized, an ap
propriate ignition voltage is impressed across
the electrodes 6 and 1. However, since the cir
cuit per se forms no part of the present invention,
further detailed description is believed super
?uous.
10
Although the discharge device 4 as shown can
be employed for numerous purposes and circuits,
it is illustrated as a control device for controlling
or otherwise ai‘n‘xed to a ?exible metallic dia
the supply of energy to a load. As a typical pur
phragm H] of copper or the like, which latter at
pose, it is shown in Fig. 1 as a control tube for a
its peripheral edge I2 forms an hermetic seal 15 high voltage circuit and for such application one.
with the vitreous envelope 5; and exteriorly of
end of the secondary winding 21 of a high ten
the device 4 such leading-in and supporting con
sion transformer 28 is grounded at 25; and since
ductor is provided with a metallic terminal I3 of
copper, tantalum, molybdenum, or the like,
the cathode is also grounded at 25, as above men
tioned, a connection is thus completed to the
welded or otherwise rigidly a?ixed thereto which 20 cathode 1 through the leading-in and supporting
thus constitutes an integral part of the leading
conductor 9. The remaining end of the second
in and supporting conductor 8. The leading-in
ary winding 21 connects “to load” as indicated by
and supporting conductor 9 is similarly secured
such legend, as does the anode I‘! through the
to a metallic terminal M of copper, tantalum,
leading-in and supporting conductor l8 and ter
molybdenum or the like, which thus forms an 25 minal M. The primary winding 29 of the trans
integral part thereof and, as shown, such termi
former 23 may be connected to a suitable source
nal is provided with an enlarged diameter por
of the customary domestic potential of 115-230
tion having a feather edge l5 also forming an her
volts. When an impulse of electrical energy
metic seal with the vitreous envelope 5. Both of
passes through the primary winding 26 of the
the leading-in and supporting conductors are
30 transformer 22, a high voltage impulse is induced
provided with suitable ba?ies I5 for the purpose
in the secondary Winding 23 of this transformer
of preventing hot metallic particles from the
22 which voltage is impressed across the starting
electrodes 6 and ‘I from falling in the vicinity of
electrode 6 and cathode ‘I. Since these electrodes
the seals and thus destroying the same.
are closely spaced, as above noted, a high poten
An anode ll of a refractory metal such as tung
35 tial gradient results which initiates a “field emis
sten, molybdenum, or the like, and of substantial
sion arc” discharge therebetween. The space
ly U-shape, is also supported by a leading-in
charge, and consequently the impedance of the
conductor l8 so as to position the anode a short
device, is accordingly reduced and an electron
distance from the electrodes 6 and ‘l and over
discharge almost instantaneously occurs between
lapping the gap between these latter electrodes.
the cathode ‘l and the anode I‘! as hereinbefore
This leading~in and supporting conductor 18 is 40 mentioned, which enables the “load” to be ener
secured to a terminal H) which is identical to and
gized from the transformer 28.
forms an hermetic seal with the envelope 5 in the
As previously mentioned herein and as set forth
same manner as previously mentioned with re
in the concurrently ?led copending \application,
spect to the terminal l4. After assembly of the
Ser. No. 459,775, there is a gradual wearing away
device it is exhausted to a high degree of evacu 45 of the ignition electrodes and particularly the
ation through an exhaust tip 20 with the various
starting electrode 6. Moreover, the electrode
metallic parts being thoroughly degasi?ed, as is
spacing between the starting electrode 6 and
customary in the art, so that satisfactory opera
cathode ‘I, even though it might not be measured
tion is entirely independent of vapor or gas pres
directly, is nevertheless a function of the voltage
50
ent in the device.
required to initiate the “field emission arc” dis
If desired, however, a metal vapor such as mer
charge. Consequently, this wearing away of the
cury may be introduced into the envelope 5 prior
electrodes causes an increase in the voltage re
to “tipping off” at 20, which also results in satis
quired to initiate the arc, as above mentioned,
factory operation so long as its pressure is such
not only affects the characteristics of the
that the spacing between the ignition electrodes 55 which
device, but considerably shortens its useful life.
is less (and preferably many times less) than
Yet by knowing the relationship of voltage and
the mean free path of electrons in the vapor so
electrode spacing, which naturally varies with
that ignition and operation of the device is en
different materials and electrode con?gurations,
tirely independent of the mercury vaporfpresent.
In the embodiment as shown in Fig. 1 the elec 60 and by holding the spacing constant, the voltage
will likewise be maintained constant, for any
trode 6 constitutes the starting electrode, while
tendency of voltage variation is an indication
the electrode 7 is the cathode. For the purpose
that an adjustment of the electrode spacing is
of initiating a “?eld emission arc” between these
required
in order to maintain constancy of igni
two electrodes, a suitable source of energy is pro
tion voltage.
vided such, for example, as a high tension trans
In accordance with the present invention, a
former 22, the secondary winding 23 of which
constant voltage is obtained by a mechanical
has one end connected to the terminal I3 and
structure for effecting controlled movement or
hence to the starting electrode 6 through the
adjustment of the electrode spacing. Such
leading-in conductor 8, while the remaining end
structure, as illustrated in Fig. 1, comprises a
is grounded at 24. Since the terminal 14 is also
base member 30 of suitable insulating material to
grounded at 25, a circuit from the secondary
which a block 32 is secured, such as by means of
winding 20 to the cathode ‘l is completed through
a screw 33. The block 32 is provided with are
the leading-in and supporting conductor 9. In
order to energize the transformer 22, the primary
cess engageable by the metallic terminal [4 of
winding 26 thereof is connected to a suitable ' r the device.
A further block 34 is arranged to
2,407,979
5
slide between a pair of guides 35 upon the upper
surface of the base til. For the purpose of mov
ing the block 34-, the base 35! is provided with 2.
lug 36 threadedly engaged by an adjustment
screw 31 having a knurled handle 33 and pro
vided with a collar 39 ?tting into a recess pro
away due to evolution of metallic particles caused
by the “?eld emission arc” discharge.
lthough one embodiment of the present in
vention has been shown and described, it is to be
understood that other modifications may be made
without departing from the spirit and scope of
the appended claims.
vided in a retainer plate All. The block 313, simi
We claim:
lar to the block 32, is provided with a recess which
1. A discharge device whe'ein operation is ini
is engaged by the metallic terminal 13 forming
an integral part of the leading-in and support 10 tiated by ?eld emission of electrons comprising
a pair of oppositely disposed spaced electrodes
ing conductor 8.
between which a ?eld emission are discharge
During operation of the device as above noted,
occurs upon the application of a potential thereto
when the electrodes 6 and ‘I wear away to the
point where there is a tendency for the ignition
and subject to deterioration tending to increase
voltage to vary, it is only necessary for an oper 15 the gap therebetween during operation, an anode
ator to rotate the knurled handle 33 of the ad
in juxtaposition to said pair of electrodes for sup
justing screw 37 in a counter-clockwise direc
porting an electron discharge with one of the
tion, and since the adjusting screw threadedly
electrodes of said pair immediately following the
engages the lug 36 and loosely engages the block
?eld emission are discharge between said pair of
345, the latter will be slid along the base 30 to the 20 electrodes, and means disposed exteriorly or" said
left, as shown in Fig. 1. Inasmuch as the me
device and operable by an operator at will to cause
tallic terminal 13 forming an integral part of the
relative movement between said pair of electrodes
leading-in and supporting conductor 8 ?ts into
to maintain the spacing therebetween substan
the block as, the leading-in and supporting con
tially constant during the useful life of said device.
ductor 8, together with the starting electrode 6 25
2. A discharge device wherein operation is ini
supported thereby, will be moved due to the flex
tiated by ?eld emission of electrons comprising a
ible metallic diaphragm Ii! which accordingly
pair of oppositely disposed spaced electrodes be
prevents a strain being placed upon the hermetic
tween which a ?eld emission are discharge occurs
seal where the leading-in and supporting con
upon the application of a potential thereto and
ductor passes through the wall of the device. 30 subject to deterioration tending to increase the
rli‘his movement of the adjusting screw 31 will ac
gap therebetween and the voltage required to ini»
cordingly cause the electrode 6 to be moved in
tiate the ?eld emission arc discharge during
closer proximity to the cathode ‘l, thus again
operation
said device, an anode positioned ad
setting such spacing to that desired and main»
jacent said pair of electrodes for supporting an
taining the spacing together with the ignition 35 electron discharge with one of the electrodes of
voltage substantially constant.
~
said pair immediately following the ?eld emission
It should also be noted that although the lead
are discharge between said pair of electrodes, and
ing~in and supporting conductor 8 has been
means disposed exteriorly of said device and op
shown as secured to the ?exible diaphragm iii,
erable at will by an operator to maintain the
such is not absolutely essential, but, on the other 40 voltage required to initiate the ?eld emission are
hand, the hermetic seal formed between the lead
discharge constant despite deterioration of said
ing-in and supporting conductor 8 and the enve
pair of electrodes during the useful life of said
lope 5 may be identical to that of the leading-in
device.
and supporting conductor 9. In other words, the
3. A discharge device wherein operation is ini“
leading-in and supporting conductor 8 may be
tiated by ?eld emission of electrons comprising a
provided with a terminal member I4 and move
pair of oppositely disposed spaced electrodes be
ment of the leading-in and supporting conductor
tween which a field emission arc discharge occurs
still obtained by regulation of the adjusting screw _
upon the application of a potential thereto and
31. This is because appreciable ?exibility results
subject to deterioration tending to increase the
even with the provision of a metallic terminal,
gap therebetween during operation, an anode
such as shown at l4, allowing movement of the
positioned adjacent said pair of electrodes for
leading-in conductor without placing undue
supporting an electron discharge with one of the
strain on the seal, particularly since the adjust
electrodes of said pair immediately following the
ment of the spacing between the electrodes 6 and
field emission arc discharge between said pair of
‘l at any time is exceptionally minute, being of 55 electrodes, and a mechanical member disposed
the order of .010 inch as above noted. However,
exteriorly of said device and operable at will by
in some instances it may be preferable to employ
an operator to cause relative movement between
a flexible metallic diaphragm such as shown at
said pair of electrodes to maintain the spacing
ll) in Fig. 1.
therebetween substantially constant despite de
From the foregoing description it thus becomes
terioration of said pair of electrodes during the
obvious to those skilled in the art that an elec
useful life of said device.
tron discharge device wherein operation is initi
4. A discharge device wherein operation is ini
ated by a “?eld emission are” discharge is here
tiated by ?eld emission of electrons comprising
in provided in which the spacing between the
a sealed envelope. a pair of oppositely disposed
electrodes, and hence the voltage required to 65 spaced electrodes in said envelope between which
initiate such discharge, is maintained substan
a ?eld emission are discharge occurs upon the
tially constant. Moreover, such constancy is ob
application of a potential thereto and subject to
tained at the will of an operator by simple ad
deterioration tending to increase the gap there
justment of a mechanical member disposed ex
betwcen and the voltage required to initiate the
teriorly of the device which upon operation causes 70 ?eld emission arc discharge during operation of
controlled movement of the leading-in and sup
said device, a leading-iii and supporting con
porting conductor for one of the electrodes, to
ductor for each electrode of said pair and form
ing an hermetic seal with said envelope, an
gether with the electrode carried thereby, so that
anode positioned adjacent said pair of electrodes
a ?xed spacing is maintained between the ignition
electrodes, thus compensating for their wearing 75 for supporting an electron discharge with one of
2,407,979
7
the electrodes of said pair immediately following
the ?eld. emission are discharge between said
pair of electrodes, and a member disposed exteri
orly of said envelope and operable at will by an
operator to cause movement of one of said lead
ing-in and supporting conductors together with
the electrode supported thereby for the purpose
of maintaining the spacing between said pair of
electrodes substantially constant despite deteri
oration of the latter during the useful life of said
device.
5. A discharge device wherein operation is ini~
tiated by ?eld emission of electrons comprising
a sealed envelope, a pair of oppositely disposed
spaced electrodes in said envelope between which
a ?eld emission are discharge occurs upon the
application of a potential thereto and subject to
deterioration tending to increase the gap there
between and the voltage required to initiate the
?eld emission arc discharge during operation of
said device, a leading-in and supporting conduc
tor for each electrode of said pair and forming
an hermetic seal with said envelope, an anode
hermetic seal between one of said leading-in and
supporting conductors and said envelope, an an
ode positioned adjacent said pair of electrodes
for supporting an electron discharge with one of
the electrodes of said pair immediately following
the ?eld emission are discharge between said pair
of electrodes, and a member disposed exteriorly
of said envelope and engageable with the leading
in and supporting conductor for one electrode of
said pair and operable at will by an operator to
cause movement of said conductor at the resilient
seal with said envelope accompanied by movement
of the electrode supported thereby for the pur
pose of maintaining the spacing between said
pair of electrodes substantially constant despite
deterioration of the latter during the useful life
of said device.
'7. A discharge device wherein operation is ini
tiated by ?eld emission of electrons comprising
a sealed envelope, a pair of oppositely disposed
spaced electrodes in said envelope between which
a ?eld emission are discharge occurs upon the
application of a potential thereto and subject to
positioned adjacent said pair of electrodes for
deterioration tending to increase the gap there
supporting an electron discharge with one of the 25 between and the voltage required to initiate the
electrodes of said pair immediately following the
?eld emission are discharge during operation of
?eld emission arc discharge between said pair of
said device, a leading-in and supporting conduc
electrodes, and a mechanical member engageable
tor for each electrode of said pair, a ?exible me
with the leading-in and supporting conductor for
tallic diaphragm secured to one of said leading-in
one of the electrodes of said pair exteriorly of 30 and supporting conductors and forming an her
said envelope and operable at will by an operator
metic seal with said envelope, an anode posi
to apply a tension to said conductor to cause de
tioned adjacent said pair of electrodes for sup~
?ection thereof with attendant movement of the
porting an electron discharge with one of the
electrode supported thereby for the purpose of
electrodes of said pair immediately following the
maintaining the spacing between said pair of
?eld emission are discharge between said pair of
electrodes substantially constant despite dete
electrodes, and a member disposed exteriorly of
rioration of the latter during the useful life of
said envelope and engageable with the leading-in
said device.
and supporting conductor for one electrode of
6. A discharge device wherein operation is ini
said pair and operable at will by an operator to
tiated by ?eld emission of electrons comprising 40 cause ?exing of said diaphragm and attendant
a sealed envelope, a pair of oppositely disposed
movement of one of said leading-in conductors
spaced electrodes in said envelope between which
together with the electrode carried thereby for
a ?eld emission are discharge occurs upon the
the purpose of maintaining the spacing between
application of a potential thereto and subject to
said pair of electrodes substantially constant de
deterioration tending to increase the gap there 45 spite deterioration of the latter during the useful
between and the voltage required to initiate the
life of said device.
?eld emission are discharge during operation of
JOHN H. FINDLAY.
said device, a leading-in and supporting conduc
CLARENCE E. DAWLEY.
tor for each electrode of said pair, a resilient
ANDREW PFEIFFER.
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